Electric contact assembly



United States Patent Ofiice 3242295 Patented Mar. 22, 1966 3,242,295 ELECTRIC CGNTACT ASSEMBLY Walter Holzer, Uberlngen (Bodensee), Germany '(Drosteweg 19, Meersbnrg (Bodensee), Germany) Filed .iuly 15, 1963, Ser. No. 295,()38 Claims priority, application Germany, Oct. 11, 1962, H 47,122 5 Claims. (Cl. 200-166) The invention relates to a flat contact, in the form of a stamped member of which one end lies on the conductive overlay of a printed circuit and the other end lies detachably on the conductive overlay forming the opposed contact.

The purpose of the invention is to connect the stamped member forming the fiat contact to the base on which the conductive overlay of the printed circuit is located in such a way that easy rapid nounting is possible.

Contact members have hitherto been connected to printed circuits by riveting and additionally soldering one fixed end of the contact to the conductive overlay. The other end was then lifted off the opposed contact. This positive, friction like connection was necessary because one had to allow for the base to shrink and then, if there was riveting, for the pressure of the contact onto the printed circuit to be relaxed or to become so Weak as to make scorching or spark formation inevitable.

The invention aims to connect the flat contact, or the stamped member forming the fiat contact, to the base of the printed circuit in such a way that the contact can be removed later, and so that if the base shrinks the contact still exerts sufficient pressure on it. It also aims to dispense with riveting and soldering.

According to the invention, the end which is fixed onto the conductive overlay is in the form of a hearing and is pressed against the base by the action of a spring provided there, so that the fiat contact is connected to the base of the printed circuit only by a force.

As a result of this construction there is always sufiicient pressure between the flat contact and the printed circuit. The fact that this pressure point is designed as a hearing means that when the contact is operated, i.e. vertically reciprocated, the hearing can move over the printed circuit, even if only slightly. The flat Contacts can now be made of cheaper materials, for example of materials of low elasticity, as the emphasis is no longer so much on the bending which takes place when contact is made as on the pivoting of the contact about a point of rotation. Bending of the contact is necessary only insofar as sufficient pressure must be obtained at the end of the contact, as it is alternately lifted oti and replaced on the printed circuit.

There are a great many ways in which the other end of the flat contact can be coupled to the printed circuit by a force.

One of these ways is for the distance between the spring which couplcs the flat contact to the base of the printed circuit in a friction-like manner, and the end permanently lying on the base to be less than the distance from the spring to the end which bears on and can be lifted oti the base.

In this construction the spring has a different action on the two ends of the flat contact. Its strongest action is exerted on the end which has the bearing and which must always remain on the printed circuit, whereas the spring is further away from the other end. The use of a spring of this type makes it possible to use such contacts edgewise, as the bending of the contact need no longer be used as a returning force. The returning force is provided by the spring which also connects the flat contact to the base of the printer circuit. By using such stamped members edgewise it now becomes possible to juxtapose a great many contacts in close, parallel or otfset arrangement; safety is increased, and far less space is required, for example for control discs in fully automatic washing machines or for machine tool circuits. Assembly is now very much Simpler, and dismantling particularly easy.

In other constructions a projection adjoins the end of the contact designed as a bearing, the projection extending through a slot in the lower portion and having a lug for securing the spring, which bears on the other side of the conductive overlay on the base.

In this embodiment the hearing and the contact making part are at the outermost ends of the contact, and these two ends are on the same side as the printed circuit.

In another Construction the end of the contact which is fixed to the base has a sinuous angled portion, of which one side extends through the base and carries a raised portion forming the hearing, while the end of the angled portion on the opposite side of the base carries the lug for securing the spring.

In this embodiment the conductive overlay connected to the hearing and the conductive overlay connected to the removable contact are on opposite sides of the base. The spring for securing the flat contact to the base is here mounted at one end of the contact, while the other end carries a lug; the lug may, for example, be moved by a cam so as to lift the contact oti the base or replace it thereon.

In other embo dinents of the flat contact, the end of the contact which is fixed to the base is U-shaped, the opposed linbs being pressed together against both sides of the base by a projection when the contact, which is biassed by sinuous stamping, is inserted in flat slots and connected to the base.

A Construction of this type may be used, for example, for transmitting quite high loads, since the hearing is now no longer on the conductive overlay but is brought inside the contact. Here the contact is connected to the side which cannot be lifted by opposed lugs, with the result that the current density can be reduced since the contact surfaces are larger.

The contact surfaces may also be enlarged by designing two adjacent flat contacts as a double contact, of which the projections or adjacent lugs are interconnected and connected to the base by a spring.

These double Contacts, which are known in the field of relays for increasing Operating safety, may here be formed from adjacent flat contacts. Each of these strips can move freely and independently in its plane of operation, so that tolerances are compensated for and absolute safety in contact making guaranteed.

Further according to the invention the contact track with the fixed contact and the point of rotation is on the underside of the plate, and the contact member extends through the plate. This makes it possible for the contact member to be held edgewise by guides on the plate.

Other possible constructions will become apparent from the drawing and description. In the drawings:

FIG. 1 shows diagrammatcally how a flat contact is fixed to the base of a printed circuit,

FIG. 2 is a plan view of FIG. 1, with double contacts,

FIG. 3 is a diagrammatic view from below of the point of attachment, in the direction of the arrow in FIG. 1 slight ly enlarged,

FIG. 4 shows a flat contact with the raisable contact in front and then the Operating cam,

FIG. 5 shows a view similar to FIG. 4, with a different Operating cam,

FIG. 6 s similar to FIG. 1 and illustrates another way of fastening the contact,

&242395 FIG. 7 shows another embodiment of the cam and of the contact making part behind it,

FIG. 8 shows another way of securing the contact to the base,

FIG. 9 shows the projections for double Contacts, which projections are connected by the spring and extend through the base as shown in FIG. 2.

FIG. 1 shows the base 1, which may be made of hard paper -or be a piece of plastics overlaid with contact tracks. conductive contact tracks 3, 4 are provided in known marner on the side 2 of the base. The base has slots 5, 6 which also serve to guide the flat contact 7; this is a stamped member arranged edgewise, which is vertically reciprocated in the direction of the arrow 9 by the operating cam 8. When it is raised the raisable contact 10 is lifted off the base. The fixed contact 11 must remain permanently on the base. The reciprocating movement of the fiat contact 7 in the direction of the arrow 9 is made possible by the hearing 12 provided at one end of it. The contact 7 is connected to the base 1 by the round, cylindrically coiled spring 13. The projection 14 near the hearing 12. has a stamped out portion 15 in which two opposed lugs 16, 17 are provided to guide the spring 13. As the slot is only slightly wider than the fiat contact 7 and the projection 14 it will be seen, particularly from FIG. 3, that the spring 13 lies on the base 1 on both sides of the slot 5; and since it is on the opposite side of the base 1 to the conductive overlays, it presses the contact 7, together with the fulcrum hearing 12 and raisable contact 10, down onto the conductive contact tracks 3, 4 of the printed circuit. The spring 13 is a shorter distance away from the bearing 12, i.e. from one end of the contact, than from the raisable contact at the other end. As a result the pressure of the contact into the conductive track 3 is greater here than onto the conductive track 4. The amount of pressure required for the track 4 is only the usual pressure of conventional resilient contacts.

FIG. 2 shows that an additional flat contact 18 can be provided adjacent the flat contact 7. FIG. 9 shows that the lugs 17, 20 respectively on the projection 14 on one contact and on the projection 19 on the other contact can be arranged at quite different heights. The spring 13 adapts itself to existing tolerances and differences in height and nevertheless ensures uniform operation of the contacts connected in parallel. FIG. 4 shows that the removable contact 10 may also be at the end of the flat contact 7; behind it the Operating cam 8 penetrates the base 1 through the slot 6, which also acts as a guide for the contact 7.

In FIG. 5 like numerals denote like parts. Here the contact 7 is guided by a lug 21 which is used to operate the latter.

In FIG. 6 the contact has a U-shaped conformation 22 at one end, and the other end is shaped as in the preceding drawings. The bearing 12 is arranged in this U- shaped portion. Another flat slot 23 in the base provides a passage for the limb 24 of the contact. The limb 24 again ends in a projection 19 with a lug 17 which holds the spring 13 in position. This embodiment retains the principle of coupling the flat contact 7 to the base 1 by a spring or force connection. The cam 8 may have an angled portion 25 as shown in FIG. 7. The conductive contact tracks 3, 4 may be on different sides of the base 1 as shown in FIGS. 5 and 6.

In FIG. 8 the contact 7 has a sinuous stamped out portion 26, which both generates the returning force for the removable contact 10 when the latter is lifted ofi its base, and provides the pressure eXerted by the hearing 12 on the conductive contact track 3. An additional projection 27 serves to hold the contact in position.

This Construction is suitable for cases where the contact is pressed onto a conductive base 1. In the FIG. 6 embodiment it is, so to speak, threaded through, and in the FIG. 1 embodiment merely placed on the base.

'Obviously a great many other constructions are possible, but these all come within the scope of the invention if they include resiliently connecting a fiat contact, which is not resilient in its operational direction, to the base of a printed circuit.

What is claimed is:

1. A contact assembly comprisng a base having spaced contact tracks mounted thereon, an elongated flat contact member mounted edgewise on said base, said contact member having contact points adjacent each end thereof Contacting respectively said spaced contact tracks, said base having an opening therethrough, one end of said fiat contact member having a camming projection extending through said opening, and the other end of said contact member having means resiliently clamping said member to said base and said contact tracks.

2. A contact assembly comprisng a base having spaced contact tracks mounted thereon, an elongated flat contact member mounted on said base edgewise thereof, said contact member having contact points adjacent each end thereof Contacting respectively said spaced contact tracks, said base having spaced openings extending therethrough, one end of said fiat contact member having a camming projection extending through one of said openings, and the other end of said member having a part projecting through the other of said openings, said part carrying a coiled spring in resilient contact with said base and resiliently clamping said contact member to said base and said contact tracks.

3. A contact assembly as defined in claim 2, said flat contact member Operating as a lever and having a fulcrum hearing on the side of said base opposite said spring, and said fulcrum bearing carrying one of said contact points and contacting one of said tracks.

4. A contact assembly as defined in claim 3, said fulcrum bearing being positioned between said spring and said camming projection.

5. A contact assembly as defined in claim 3, said spring being positioned between said fu lcrum hearing and said camming projection.

References Cited by the Examiner UNITED STATES PATENTS 3,147,359 9/1964 Hanna 200-166 KATHLEEN H. CLAFFY, Pr'mczry Exam'ner.

BERNARD A. GILI-IEANY, Exam'ner. 

1. A CONTACT ASSEMBLY COMPRISING A BASE HAVING SPACED CONTACT TRACKS MOUNTED THEREON, AN ELONGATED FLAT CONTACT MEMBER MOUNTED EDGEWISE ON SAID BASE, SAID CONTACT MEMBER HAVING CONTACT POINTS ADJACENT EACH END THEREOF CONTACTING RESPECTIVELY SAID SPACED CONTACT TRACKS, SAID BASE HAVING AN OPENING THERETHROUGH, ONE END OF SAID FLAT CONTACT MEMBER HAVING A CAMMING PROJECTION EXTENDING THROUGH SAID OPENING, AND THE OTHER END OF SAID CONTACT MEMBER HAVING MEANS RESILIENTLY CLAMPING SAID MEMBER TO SAID BASE AND SAID CONTACTS TRACKS. 